* fix(products): update pricing on products
* fix(test): pin coffee price in cart-limit fixture
TestConvertCartLimit's quantities and expected totals were keyed to
the original 500-cent latte price. After the product price bump in
1ce63fb, coffee_id=4 became 2500 cents, so under_cap/at_cap subtests
overshot the $200 cap and over_cap's expected total magnitude was
wrong by 5x. Override coffee_id=4's price to 500 in test setup so the
cap math stays stable regardless of seed changes.
prices stored as float64 could lead to rounding errors when converting to cents for stripe (19.99 * 100 = 1998.99... truncating to 1998). canged Coffee.Price to int, storing cents directly. Updated the seed data, fallback products, API handlers, and all TUI display code to be in sync with this change.
